Method and device for ozonization of a fluid

ABSTRACT

In order to enhance the operating safety of the ozonizer (1), there is provided between the ozonizer (1) and the mixer (2) a valve (3) operating without any outer energy and in a single flow direction. The mixture is clamped directly to the ozonizer to minimize the self-dissociation of the ozone formed in the ozonizer (1) during the transport to the mixture (2). The disclosed method may be used to sterilize water or gas elements for example evacuation air. It may also be used for the oxidation of chemical elements.

Ozone is known as one of the most effective oxidizing agents and it istherefore used for the sterilization of fluids, e.g. drinking water,waste water, mud or exhaust gas, as well as for the non-microbic, i.e.chemical treatment of fluids, e.g. industrial waste water with organicload material.

A great advantage with the use of ozone for carrying out sterilizationof fluids is its own decay, i.e. surplus ozone decays into oxygen andprevents a further load on the environment as for example in the case ofthe sterilization with chlorine. Moreover, no storage is necessary,because ozone can be produced on location from oxygen, e.g. out of air.

The use of ozone for carrying out sterilization of fluids as well as adevice for it have been known for a long time. But up to now a reliableoperation of the ozonizer has stood in the way of its widespread use.

An analysis has found that for the majority of the cases of damage areturn flow of fluid to be brought into contact with the ozone-bearinggas into the ozonizer is responsible: if the fluid is a liquid, ashort-circuit current is generated in the ozonizer between theelectrodes. If the fluid is a gaseous fluid, a condensation of humidity,i.e. water vapor, on the cooled electrode surfaces causes a change inthe electrode gap, so that a local high-energy spark discharge candestroy the ozonizer. The destruction of the ozonizer is carried outidentically by solid matter particles deposited on the electrodesurface.

An introduction of humidity, or solid matter particles, respectively,into the ozonizer is eliminated to a large extent according to the stateof the art by gas driers and dust filters. These safety measures areinsufficient when the ozonizer is of the spark discharge type and iscooled by the fluid to be treated. When the fluid is cold, the relativehumidity of the air, even after passing a drier may be too high, so thatcondensation of water occurs in the spark discharge area which maydestroy the ozonizer. It is therefore the object of the invention todisclose a method and an implementation of the method that do not sufferfrom the described drawbacks.

By using a valve that operates without the requirement of foreign energyand only allows one direction of flow, preferably a nonreturn valveequipped with a membrane, an intrusion of fluid into the ozonizer isalso prevented when the ozone equipment is turned off, i.e. theprotection is also ensured in the case of a power failure. A mixerarranged on the ozonizer minimizes the ozone transportation time betweenthe ozonizer and the mixer. Due to the minimal transportation time thenatural ozone decay is minimized, so that a maximum of the ozoneproduced in the ozonizer is admixed to the fluid and can becomeeffective with it.

Further development of the invention increases the operational safety ofthe method by using a measuring device for monitoring the relativehumidity determines a too high humidity content of the gas and therebyinterrupts the ozonizer current. In this way a condensation of water onthe cooled electrodes is prevented. Moreover, by using dry gas the ozoneyield is increased and the formation of nitrous gases is minimized.

Monitoring of the gas throughput ensures a continuous feeding of theozonizer with fresh gas and thus a continuous production of ozone. Ifthe gas throughput falls below a preferably adjustable nominal value, inthis case also the ozonizer current is interrupted.

In the preferred use of a measurement device for determining therelative humidity as well as a gas throughput meter the error reportingsignals are practically correlated by an "OR-connection". The resultingsignal of this connection can e.g. be used to drive an alarm device(acoustically and/or optically) and/or to drive further elements, e.g.the fluid pump or the water vapor removal device.

Of course the error reporting signal of each individual measurementdevice can also be processed further separately.

In an embodiment of the method the gas to be ozonized is conductedbefore its entry into the ozonizer through a water vapor removal device,e.g. a dryer filled with silica gel with two columns.

So that no solid material particles, by which e.g. dust from thesurroundings or wear material from the drier can be understood, intrudeinto the ozonizer or the measurement device(s), a filter is practicallyinstalled into the connecting line for the gas to be ozonized betweenthe drier and the ozonizer.

In a further embodiment of the method, the fluid is preventilatedozone-free with a gas containing oxygen before its entry into the mixerwhere it comes into contact with the ozone-bearing gas. Thispreventilation serves to activate e.g. microorganisms present in theform of spores in the fluid, whose breathing system begins to work inthis way. Only if the breathing system is activated can the ozone carryout its sterilizing effect.

So that the microorganisms killed off cannot serve as new nutrientmedium for eventually not killed off microorganisms, in a furtherembodiment of the method, the fluid is filtered after coming intocontact with the ozone containing gas. The filtered fluid is then fed toa further mixer in which an additional dosing of ozone is effected.Because the fluid flowing out of the filter is to a large extent free ofactive microorganisms capable of division or dead cellular material theozone dosed in the further mixer serves mostly to build up a sterilizingozone buffer in the fluid. In this way it can be prevented that theozone treated fluid which is preferably stored in a storage container issubjected to a new attack by microorganisms, or that microorganismsstill in active condition eventually passing through the filter begin topropagate. So that the filter is not loaded with additionalmicroorganisms in case of required cleaning it is practical to flushback the filter with already ozonized fluid.

A preferred embodiment of the device is equipped with a main independentpower supply. It can be a generator with a lined up internal combustionengine. An accordingly equipped device can serve e.g. as a mobiledrinking water treatment device among other things in remote areas or incases of disasters.

Apart from the treatment of drinking water, a treatment, i.e.sterilization of waste water or flow-capable mud or rediluted mud e.g.from sewage-treatment plants is possible with the method according tothe invention.

Further all oxidizable substances can be oxidized which is especiallyimportant for the removal or transformation of bad-smelling materials ormaterials impairing taste.

In the following, the invention is explained with reference to anapplication example.

The sole FIGURE shows a block-diagram of a device used to treat brackishwater polluted by liquid manure. The device comprises a power supply 9that operates independent of the mains, which supplies power both to atransformer indicated as "Trafo" and to the relay marked "t-Relay".

A tube-shaped ozonizer 1 is vertically mounted in a water conduit 11. Inthis way the water cools the ozonizer. A venturi mixer 2 isflange-connected with the ozonizer immediately via a PVC coupling piece12. The water flowing through the venturi mixer sucks air to be ozonizedunder the influence of the underpressure building up within the mixerthrough the silica gel filled drier 13, conduit 14 and the ozonizer 1,in which part of the air oxygen is transformed into ozone according tothe known reaction equilibrium. The ozone bearing gas leaves theozonizer 1 via a conduit containing the membrane equipped nonreturnvalve 3 which works without requiring foreign power supply, into themixer 2.

In the highly turbulent contact zone of the mixer the ozone bearing gasis is dispersed as fine bubbles into the water. Thereby a large specificgasliquid contact area is created and thus an optimal ozone transferinto the water achieved.

In the connecting conduit 14 between drier 13 and ozonizer 1 an airthroughput meter 5 and a measurement device 4 for determination of therelative humidity are each installed. These serve to monitor theoperating conditions in the ozonizer as is explained in the following.

Ambient air is sucked into one 13' or two columns 13,',13" of the drierdue to the underpressure created in the venturi mixer. The silica gelpresent in the drier column removes the water vapor content from theair. To control this drying process the humidity meter 4 continuouslymeasures the relative humidity of the air flowing out of the drier. Ifthis humidity rises above a manually adjustable nominal value, theelectronic comparing unit 6' following the humidity meter emits asignal. The magnitude of this nominal value depends on the applicationand is especially influenced by the temperature of the coldest part ofthe ozonizer. It is very important that the temperature does not reachor fall below the condensation point at this point of the air to beozonized. Because the ozonizer is water-cooled, i.e. through thebrackish water to be sterilized, the temperature can be approximatelyused to determine the nominal value for the comparing unit 6'.

It is also possible to use the output signal of the comparing unit 6'for redirecting the air flow over the two columns 13', 13" and at thesame time starting a thermal regeneration process in the column 13' usedup to now. But because a air throughput meter 5 is used apart from thehumidity meter 4 for monitoring the air throughput through the ozonizer,the said signal is logically combined with the signal of the humiditymeter by an "or-connection unit" 6". The redirection of the dryercolumns is solely effected by timing relay marked Relay in the drawing.When the timing relay is activated it closes the valve connecting forexample drier column 13' to conduit 14 and switches on heating line V, Hto that drier. At the same time it opens the valve connecting driercolumn 13 to conduit 14. The air throughput meter is designed as a flowmeter. A photoelectric device or a proximity switch senses the positionof the float body. If this falls under an adjustable nominal value theair throughput meter emits a signal. The nominal value of the airthroughput meter is determined by the requirement for ozone whichcorresponds to a certain air throughput.

The output signal of the "or member" 6" thus controls a relay 6"', whenthe air humidity nominal value is exceeded as well as when the humiditydrops below it, which interrupts the ozonizer current and activates analarm unit (horn, siren, or blinking light) at the same time. Becausesilica gel dust can form in the dryer if it is operated over a longerperiod of time, or dust can intrude from the environment through thedryer into the connecting conduit 14 to the ozonizer, a fine dust filter15 is installed in direction of air flow in front of the measurementdevices.

The mixture of water and ozone-bearing gas leaving the mixer 2 is guidedthrough a tube conduit 16, the length of which is determined by thedesired contact time of the two phases, into a collection container 10.In this tube conduit static mixing elements can be additionallyinstalled. But it is also possible to install a phase-dividing element,e.g. a gas separator, in front of the collection container. The gasseparator is preferred in particular for swimming pool watersterilization installations, so that no gaseous ozonze layer which wouldendanger the health of the swimmers could form over the swimming poolthat has taken over the function of the collection tank in this case.

Because sporelike, i.e. not actively breathing microorganisms are oftenpresent in brackish waters, and these can not be destroyed in the statedform by ozone, in a further development of the invention a ventilationdevice 7, for example in the form of a ventilation tank or a bubblecolumn is added in front of the ozonizer. Due to the introduced oxygenthe spore-like organisms are activated and can then be destroyed by thesubsequent contact with ozone.

One or several filters such as filter 8, e.g. active coal filters orsand filters, in front of or after the mixer clean the fluid from solidmaterials, or absorb its remaining ozone content, respectively. Thesefilters are preferably flushed back sterilely with already ozonizedfluid.

Because the fluid to be treated with ozone can also be gaseous, e.g.exhaust air, a gas-mixing element, e.g. a static mixer or also only aT-element is preferably installed instead of the venturi mixer. Becausesuch elements are usually not self-suctioning, a gas pumping organ mustbe additionally provided for the transportation of the gas to beozonized in the ozonizer.

If large amounts of fluid are to be sterilized or oxidized, the fluidflow can be distributed onto several ozonizers working in parallel. Theair treated by the drier can be conducted over a single humidity or gasthroughput meter each, respectively, or over one of these meters eachper ozonizer. It is decisive that a non-return valve is provided betweeneach ozonizer and mixer and that the mixers are directlyflange-connected with the corresponding ozonizers. It is also possibleto use a multiple mixer with individual flange-connected ozonizers.

We claim:
 1. In an ozonizer having gapped electrodes for producing anozone-bearing gas for treating a fluid, wherein said ozone-bearing gasis produced from an input gas into said ozonizer by means of electricalspark discharge between said electrodes, and wherein said ozonizer iscooled by the fluid to be treated: the method of monitoring the relativehumidity and gas throughput of the input gas before its entry into theozonizer, interrupting the operating current to the electrodes toprevent destruction of the ozonizer when the relative humidity of theinput gas exceeds a nominal value beyond which water condensation occurson the electrode surfaces narrowing the electrode gap with resultinglocal high-energy spark discharge or short-circuiting of the electrodes;and interrupting the operating current to the electrodes when throughputof the input gas is less than the requirement for the production of suchozone-bearing gas.
 2. The method of claim 1 wherein an error operatingsignal is produced when the operating current to the electrodes isinterrupted to prevent destruction of the ozonizer when the relativehumidity of the input gas exceeds such nominal value beyong which watercondensation occurs on the electrode surfaces and wherein an erroroperating signal is produced when the operating current to theelectrodes is interrupted when throughput of the input gas is less thanthe requirement for the production of such ozone-bearing gas.
 3. Themethod of claim 1 wherein the input gas is dried and filtered before itenters the ozonizer, wherein the ozone-bearing gas produced in theozonizer flows out of the ozonizer through a one-way flow valve means,and wherein the ozone-bearing gas flowing through the one-way flow valvemeans is thereafter mixed with the fluid.
 4. The method of claim 1wherein the fluid is brought into contact with oxygen or anoxygen-enriched gas before it is treated by the ozone-bearing gas. 5.The method of claim 4 wherein solid particles are filtered out of thefluid before it is treated by the ozone-bearing gas.